Moves move logic into WM instead of WS

components/mus/example/wm/window_manager_application.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/mus/example/wm/window_manager_application.h"
 
 #include "components/mus/example/wm/container.h"
 #include "components/mus/example/wm/window_layout.h"
 #include "components/mus/example/wm/window_manager_impl.h"
 #include "components/mus/public/cpp/util.h"
@@ skipping 25 matching lines @@
 }
 
 bool WindowManagerApplication::ConfigureIncomingConnection(
     mojo::ApplicationConnection* connection) {
   connection->AddService(this);
   return true;
 }
 
 void WindowManagerApplication::OnEmbed(mus::Window* root) {
   root_ = root;
+  root_->AddObserver(this);
   CreateContainers();
   layout_.reset(
       new WindowLayout(GetWindowForContainer(Container::USER_WINDOWS)));
 
-  host_->EnableWindowDraggingForChildren(
-      GetWindowForContainer(Container::USER_WINDOWS)->id());
-
   window_manager_.reset(new WindowManagerImpl(this));
   for (auto request : requests_)
     window_manager_binding_.AddBinding(window_manager_.get(), request->Pass());
   requests_.clear();
 }
 
 void WindowManagerApplication::OnConnectionLost(
     mus::WindowTreeConnection* connection) {
   // TODO(sky): shutdown.
   NOTIMPLEMENTED();
 }
 
 void WindowManagerApplication::Create(
     mojo::ApplicationConnection* connection,
     mojo::InterfaceRequest<mus::mojom::WindowManager> request) {
   if (root_) {
     window_manager_binding_.AddBinding(window_manager_.get(), request.Pass());
   } else {
     requests_.push_back(
         new mojo::InterfaceRequest<mus::mojom::WindowManager>(request.Pass()));
   }
 }
 
+void WindowManagerApplication::OnWindowDestroyed(mus::Window* window) {
+  DCHECK_EQ(window, root_);
+  root_->RemoveObserver(this);
+  // Delete the |window_manager_| here so that WindowManager doesn't have to
+  // worry about the possibility of |root_| being null.
+  window_manager_.reset();
+  root_ = nullptr;
+}
+
 void WindowManagerApplication::CreateContainers() {
   for (uint16_t container =
            static_cast<uint16_t>(Container::ALL_USER_BACKGROUND);
        container < static_cast<uint16_t>(Container::COUNT); ++container) {
     mus::Window* window = root_->connection()->NewWindow();
     DCHECK_EQ(mus::LoWord(window->id()), container)
         << "Containers must be created before other windows!";
     window->SetBounds(root_->bounds());
     window->SetVisible(true);
     root_->AddChild(window);
   }
 }